Articles having smooth, mold-imprinted surfaces are often used in trim components for interior designs, e.g. in cars or airplanes, and external parts. The automotive industry imposes stringent requirements for finished parts. Low total carbon emission, low fogging and low odor with good scratch resistance are common requirements for interior trim components such as instrument panels, door panels and quarter panel trims that are produced via injection molding.
The exterior parts, including bumper assemblies and structural modules such as front end module carriers, may require high performance filled compounds. Exterior trims like side protection trims, cowl grills, wheel arch liners and covering parts like rocker panels, body side moldings or fender liners often require specific properties in combination with good surface appearance.
U.S. Pat. No. 6,441,094 discloses impact resistant polyolefin compositions comprising two polymer fractions with different melt flow rate (MFR) values (bimodal matrix) and a rubbery phase formed by an elastomeric copolymer of ethylene. The polyolefin composition in U.S. Pat. No. 6,441,094 is described as comprising processability, mechanical and optical properties suitable for injection molded parts.
The materials used for exterior and interior trims need to deliver flexibility related properties like narrow gap tolerances, superior scratch resistance, good paint adhesion and processability.
Due to their free-flowing characteristics, different blends filled with fillers such as talcum have been used in such applications. However, the potential of talcum-reinforced blends is limited for molding of rigid finished articles, such as car dashboards, due to their inherent low flexural stiffness. Recently, low density materials capable of high mechanical performance are desired to match increasing demand for lightweight car-parts to increase fuel efficiency without compromising safety and performance.
The need exists for composite materials for molded articles with improved free-flowing properties that retain the advantages of shrinkage and impact/stiffness balance with improved surface quality.